LGG-08. MR Imaging of pediatric low-grade gliomas: Pretherapeutic differentiation of<i>BRAF</i> V600E mutation,<i>BRAF</i>-Fused and Wild-Type tumors in patients without Neurofibromatosis-1
Bibliographic record
Abstract
Abstract OBJECTIVE: The prognosis and treatment of pediatric low-grade gliomas (pLGGs) is influenced by their molecular subtype. MRI remains the mainstay for initial work-up and surgical planning. We aimed to determine the relationship between imaging patterns and molecular subtypes of pLGGs. METHODS: This is a bi-institutional retrospective study for patients diagnosed from 2004 to 2021 with pathologically confirmed pLGG, molecularly defined as BRAF fusion (KIAA1549-BRAF), BRAF V600E mutation, or wild-type (negative for both BRAF V600E mutation and BRAF fusion). Two neuroradiologists, blinded, independently reviewed imaging parameters on the initial MRI and discrepancies were solved by consensus. Bivariate analysis was used followed by pairwise comparison of Dwass, Steel, and Critchlow-Fligner methods to compare the 3 molecular subtypes. Agreement between reviewers was assessed using Kappa (k). RESULTS: 70 patients were included: 30 with BRAF fusion, 19 with BRAF V600E mutation, and 21 wild-type. There was substantial agreement between the two readers for overall imaging variables (k=0.75). BRAF fusion tumors compared to V600E and wild-type had larger size (p=0.0022), greater mass effect (p=0.0053), and increased rate of hydrocephalus (p=0.0002). BRAF fusion tumors had increased frequency of diffuse enhancement compared with BRAF V600E and wild-type (p <0.0001). BRAF V600E mutant tumors were more often located in a cerebral hemisphere (p <0.0001). Diffusion restriction (qualitatively) was uncommon but only seen in BRAF V600E (p=0.0042) with lower ADC ratio (quantitatively) (p=0.003). Additionally, BRAF V600E mutant tumors appeared more infiltrative than BRAF fusion and wild-type (p=0.0002). CONCLUSION:BRAF fusion and BRAF V600E mutant pLGG have unique imaging features that can be used to differentiate from each other and wild-type pLGG using standard radiology review with high inter-reader agreement. In the era of targeted therapy, these features can be useful for therapeutic planning prior to surgery.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".